NCERT Class X Chapter 5: Arithmetic Progression Example 8
NCERT Class X Chapter 5: Arithmetic Progression Example 8 Question: Find the 11th term from the last term (towards the first term) of the AP : 10, 7, 4, . . ., – 62. Given: An Arithmetic Progression (AP): 10, 7, 4, ..., -62 To Find: The 11th term from the last term. Formula: The nth term of an AP is given by a n = a + (n-1)d, where 'a' is the first term and 'd' is the common difference. Solution: First, find the common difference (d): d = 7 - 10 = -3 Next, find the number of terms (n) in the AP. We have a = 10, d = -3, and a n = -62. Using the formula a n = a + (n-1)d: -62 = 10 + (n-1)(-3) ⇒ -72 = (n-1)(-3) ⇒ n-1 = 24 ⇒ n = 25 The 11th term from the last term is the (25 - 11 + 1)th term from the beginning, which is the 15th term from beginning. Now, find the 15th term using the formula a n = a + (n-1)d: ⇒ a 15 = 10 + (15-1)(-3) ⇒ a 15 = 10 + 14(-3) ⇒ a 15 = 10 - 42 = -32 Resul...